The present invention relates to a fingerprint recognition apparatus and, more particularly, to a fingerprint recognition apparatus in which a sensor for detecting a fingerprint pattern is formed on an integrated circuit for recognizing the fingerprint to perform both detection and recognition of the fingerprint, and a data processing method.
In the social environment of today where an information-oriented society is progressing, the security technology has taken a growing interest. For example, in the information-oriented society, a personal verification technology for constructing, e.g., an electronic money system is an important key. In fact, verification technologies for implementing preventive measures against burglary and illicit use of cards are under active research and development (Yoshimasa Shimizu, xe2x80x9cA Study on the Structure of a Smart Card with the Function to Verify the Holderxe2x80x9d, Technical Report of IEICE, OFS92-32, pp. 25-30, November 1992).
A variety of verification schemes use a fingerprint or voiceprint for preventive measures against illicit use. Especially for fingerprint verification, many techniques have conventionally been developed. Fingerprint verification schemes are roughly classified into optical reading schemes and schemes of converting the three-dimensional pattern of a skin surface into an electrical signal and detecting it using human electrical characteristics.
In an optical reading scheme, a fingerprint is received as optical image data and collated mainly using reflection of light and a CCD image sensor (Japanese Patent Laid-Open No. 61-221883). Another scheme uses a piezoelectric thin film to read the pressure difference in the fingerprint pattern of a finger (Japanese Patent Laid-Open No. 5-61965). As a similar scheme of replacing a change in electrical characteristics caused by the touch of a skin into an electrical signal distribution and detecting a fingerprint pattern, a verification scheme of detecting an amount of change in resistance or capacitance using a pressure sensitive sheet has been proposed (Japanese Patent Laid-Open No. 7-168930).
However, of the above techniques, the scheme using light is hard to form a compact device, and use for a general purpose is also difficult, resulting in limited application purposes. The scheme of detecting the three-dimensional pattern of the skin surface of a finger using a pressure sensitive sheet or the like is hardly put into practical use and poor in reliability because of special materials and low workability.
A conventional fingerprint reading apparatus is separated from a fingerprint recognition apparatus. A fingerprint sensor for detecting a fingerprint pattern must output read fingerprint data externally from the reading apparatus. To do this, a method of scanning data detected by each pixel unit of a fingerprint sensor and externally outputting the data can be used (e.g., Teruhiko Tamori, Japanese Patent Laid-Open No. 63-310087). However, in this method, fingerprint data is output in units of data corresponding to pixel units. For this reason, when the number of pixel units of the fingerprint sensor increases, a long time (e.g., several sec) is required to output all fingerprint data. If a long time is necessary, quick fingerprint recognition of a user may be difficult.
In fingerprint recognition, the fingerprint image obtained by the fingerprint sensor must be collated with user fingerprint data registered in advance. For fingerprint collation, a feature point of the fingerprint image is extracted and compared with a registered feature point, or the fingerprint image is directly collated with a registered image. To realize the collation method, conventionally, a fingerprint recognition apparatus constructed by a microprocessor or the like is used. In the above fingerprint recognition method, processing such as generation or search of feature points or image matching ratio detection, which requires a large amount of calculation, must be performed. Hence, a high-performance processor is required to result in an expensive fingerprint recognition system. This can hardly be applied to a device such as an IC card or portable device requiring low cost.
When a fingerprint recognition system is constructed using a fingerprint reading apparatus and fingerprint recognition apparatus, a conventional fingerprint recognition system comprises a fingerprint reading apparatus 301 for obtaining a fingerprint, a fingerprint recognition apparatus 303 for collating the read fingerprint with fingerprint data in a database 302 where user fingerprint data are registered, and a processing apparatus 304 for performing processing on the basis of the recognition result, as shown in FIG. 33. In the arrangement shown in FIG. 33, the apparatuses are separated from each other. For this reason, the system allows alteration of information during data transfer between the apparatuses and consequently illicit recognition. In the arrangement shown in FIG. 33, since the apparatuses are separated, the entire fingerprint recognition system becomes bulky and can hardly be applied to a small device such as an IC card or portable device.
For collation at a higher speed, recognition apparatuses may be parallelly operated (e.g., Akihiro Nomura, fingerprint collation processing apparatus, Japanese Patent Laid-Open No. 7-271977). In this method, however, a plurality of conventional recognition apparatuses are used to recognize a fingerprint by pipeline parallel operation. Although the processing time can be shortened, the scale of the apparatus becomes large, and cost reduction and application to a portable device are difficult.
For a personal recognition system using an IC card, a method of holding data prepared from a user""s fingerprint not in a database but in an IC card and using this data for recognition as registered data of the user has been proposed (e.g., Shinji Oki, personal confirmation method for use of a card, personal confirmation system using an IC card, and IC card used for this system, Japanese Patent Application No. 9-106456). In this method as well, a memory (in this case, an IC card) for holding registered fingerprint data, fingerprint reading apparatus, and recognition apparatus are separated from each other, as in the above method. Hence, leakage of personal data from the IC card, leakage of data at the time of recognition, or alteration may occur. To recognize a fingerprint, the fingerprint reading apparatus and fingerprint recognition apparatus are necessary in addition to the IC card. Fingerprint recognition in use of the IC card is impossible without these apparatuses.
It is therefore the principal object of the present invention to apply a fingerprint recognition system that is difficult to alter fingerprint data to a compact device such as an IC card or portable device at low cost.
In order to achieve the above object, according to an aspect of the present invention, a fingerprint recognition apparatus comprises a plurality of pixel units each having a sensor element for converting a three-dimensional pattern of a skin surface of a finger coming into contact with the sensor element into an electrical signal, a sensor circuit for processing the electrical signal converted by the sensor element and outputting predetermined data, a fingerprint memory in which fingerprint data representing the three-dimensional pattern of the skin surface of the finger is registered in advance, and an arithmetic circuit for collating the data output from the sensor circuit with the fingerprint data in the fingerprint memory and outputting a collation result.
According to the present invention with this arrangement, both reading and recognition of a fingerprint at the pixel unit portion can be performed in one pixel unit.